Torani Syrup.. when does it go bad?

I have a few Torani flavors that taste (to me) like they have gone bad. They're all flavors that aren't used to much (egg nog, for example) and they taste very alcohol-ish, if that makes sense. I'm thinking that I might not like Torani's and it's just me being biased, what do ya'll think? Anyone had this problem in their shop?

I'm no expert on Torani or any other coffee syrup for that matter, but sugar based syrups will certainly ferment if given time and the bacteria to do it. No more than a bottle costs, I certainly wouldn't quibble over a partial bottle, I'd toss 'em. But that's me. maybe someone else could taste them for you? or you could gamble a latte on it, and see if it still tastes bad when mixed in a drink.